<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
<style>
 *{
            margin: 0;
            padding: 0;
        }
        .page{
              height: 200px;
        }
        .page>div{
                    float: left;
        }
        .left,.right{
                height: 200px;
                width: 200px;
                background-color: aquamarine;
        }
        .content{
               height: 200px;
               background-color: brown;    
        }
        .inner{
                 margin: 0 200px;
                 height: 100%;
        }
        .left{
                   margin-left: -100%;
        }
        .right{
                   margin-left: -200px;
        }
</style>
</head>
<body>
    <div class="page">
        <div class="content">
            <div class="inner">
                主体内容
            </div>
        </div>
        <div class="left">广告内容</div>
        <div class="right"></div>
    </div>
    
</body>
</html>